I hit Kilkenny every year for the Cat Laughs festival and the complaint has always been about the lack of decent beer.
Decent pubs:
Tynans Bridge House
Cleres (both already mentioned)
Morrisons (or is it Morriseys?)
Kytelers
Egans
Langtons stretches over 3 time zones. And if you are into contemporary/chinzy pubs there's the Hibernian, The Left Bank and the Kilford Arms.